Bug Description

I would experience 1-2 hardlocks per day when running 11.04 on my T420. System was completely unresponsive and required a hard reset. I kept an eye on syslog and Xorg.0.log, but not once did I ever get any messages during the time of the lockup. I was not able to find a correlation between any particular type of usage, nor could I reproduce the problem other than just using the system for a full day.

With little information to go on other than reports of incomplete support for Intel Sandy Bridge graphics in 11.04, I started experimenting with newer packages. After more than a week of testing, the stability of my system has greatly improved after installing the xorg-edgers PPA and the following kernel:

This affects me, too. Identical symptoms to what NTolerance reports.
NTolerance is running the next-proposed kernel, it seems. I tried that, too. No changes. Switched to 39.0 - same problems. Also with and without xorg-intel drivers from xorg/edgers made no difference. Random crashes, when connecting/removing external screen. Also experiencing random crashes when resuming from suspend to ram. I notice that changing to other X Terminal Ctrl-Alt-F8 and then back to Ctrl-Alt-F7 (can sometimes) bring X back. Sometimes not, then I restart service gdm.

Yeah, after I created this bug report I ran into some issues with the kernel I was running at the time and now I'm running Linux 3.0!

3.0.0-999-generic #201106081005

This build has not locked up on me in at least 4 full days of use. Keep in mind that I did go several days on the last kernel without lockups. I'm going to continue to test and I'll update this report with my findings.

I'm also running a slighly outdated set of packages from the xorg-edgers PPA. I enabled the PPA to get some necessary stuff, but then disabled it once I reached stability, which I have. I've attached a list of my installed xorg packages for reference.

I have these lockups on my Lenovo T520 as well. The system locks up completly but randomly. Nothing improved with the few sandybridge patches and the update to 2.6.38-10.

The only information I have, that this lockups occur running a compiz accelerated desktop.
Additionally these problems occured more often while usage of java applications (like libreoffice or oracle sql developer).

Can you ssh in to the machine from another system when this happens? If so, can you check if the 2.6.38-11 kernel that is in natty-proposed fixes this problem? There was a fix for for these symptoms in that kernel that was also included in 3.0-rc4, but if you can't ssh into the machine then it is a different bug. I do believe it should be fixed in 2.6.38-11 though going from these logs and lack of an actual GPU hang.

Kernel 3.0 runs a lot more stable but not 100%. When unplugging the machine from the docking station without turning off the external monitor before it might still crash. But it's certainly improved. I used the kernel from here:http://kernel.ubuntu.com/~kernel-ppa/mainline/
Only concern I have is that AppArmor complains about missing some compatibility patch which I haven't done any research on, yet. If you find a stock standard kernel with the patch included, let me know.

I have this "undocking without turning off ext. monitor" issue, too (I am using the 2.6.38-11 stock kernel).
Ok, but apart from that, using the 3.0 kernel solves the random hardlocks? That would already be a huge improvement. I'll maybe give it a try later.

Hello everyone. I started a new job last month where I got a ThinkPad T420 with Ubuntu 10.10 on it. I also experience this sort of assorted hard locks without any recognizable pattern. Sometimes it can go 3 or 4 days without trouble and suddenly locks 3 or 4 times in a few hours.

We have several ThinkPad laptops at the office and all of them experienced similar problems in the past. For older models, like the T410, disabling the video card at the BIOS seems to solve the problem, but for the newer T420 models this hasn't been the case. So far the suggestion here to replace the kernel with version 3.0 is the only solution reported as successful on the web.

Yesterday the new Ubuntu release came out and it comes with this newer version of the kernel. Can anyone confirm that this new release of Ubuntu solves this hard lock issue for the T420?

I can confirm that upgrading to Ubuntu 11.10 effectively solved this problem on my T420 and in another one of a colleague. Unfortunately the upgrade also removed some of the software I use the most (Lotus Notes) meaning that I'm back to Windows :(

I'm back, guess why. After 10 days of Ubuntu 11.10 I just I had an hard lock exactly in the same fashion of those I had with previous versions. Perhaps the new kernel simply reduces the frequency of these events, it doesn't avoid them absolutely.

To add another example. I also experience hardlocks with my Sandybridge T420. Keyboard input and mouse input is unresponsive, all applications stop updating.

This problem happens seemingly randomly, though it appears to happen more immediately after resuming from suspend. A hardlock ALWAYS occurs after running Open Office Calc for a few minutes. And it happens fairly often with Present. So I switched to gnumeric spreadsheet, and hardlocks are at least less frequent.

I have a T420s and its the most stable PC I have ever had. I run Ubuntu 11.10 (see how at http://dagrende.blogspot.com).
However, LibreOffice Impress crashes too often to be usable. But the machine doesn't lock.

Dag: Interesting, we both have the Intel Centrino UItimate-N wifi module. That wasn't the default--I ordered mine through lenovo directly. I wonder if it's hard-locking when it tries to connect to an AP?

dmesg appears to flush every time I reboot. What's a good way to get general hardware messages from a hard-lock?

I'm too little of a linux hacker to be able to diagnose your problem. But here is first the short lshw (thank you for hinting about this copact printout).
I also include a lsmod to show which drivers are running.

Interesting! I actually switched to Chromium about four months ago in 32bit 11.04. A Chrome release caused Chrome to start blocking for some 20s on each link/bookmark I navigated. I checked some forums and tried Chromium that worked fine. Some Chrome releases later I tried Chrome again but the problem remained, so I gave up. And what makes Chrome better? Happier color of the icon? More Google snooping functions for?

Did you have sync setup on Chromium? The link I posted above says it only happens when it syncs in the background. Also, how much do you use Firefox vs. Chromium? Obviously if you don't have Chromium open much it probably wouldn't happen.

According to the reports above, the original bug has been fixed in 11.10 Oneiric. The hardlocking bug on 11.10 with Chrome/Chromium sync is likely to be a different bug and would be easier to fix if someone filed a new bug report, thus automatically capturing all the relevant hardware info and system event logs.

This bug is not fixed oneiric. I am running Xubuntu 11.10 and still experiencing these random freezes on my T420. Subjectively seems like certain graphics-heavy applications/plugins make it happen more often. Also subjectively seems like some of the kernel options and phoronix drivers make it happen less often.

Today, for example, I had two freezes occur within 15 minutes of each other when using the new Google+ hangouts interface (on Firefox). I was able to SSH into the system, but had to reboot in order to get the display and input devices to work properly.

If there is anything I can share (logs, configuration) that will help, please let me know. Also, if grabbing an early Precise build would help, I'd also give that a try...